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ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation 

sys_oabi_semtimedop() is one of the last users of set_fs() on Arm. To
remove this one, expose the internal code of the actual implementation
that operates on a kernel pointer and call it directly after copying.

There should be no measurable impact on the normal execution of this
function, and it makes the overly long function a little shorter, which
may help readability.

While reworking the oabi version, make it behave a little more like
the native one, using kvmalloc_array() and restructure the code
flow in a similar way.

The naming of __do_semtimedop() is not very good, I hope someone can
come up with a better name.

One regression was spotted by kernel test robot <rong.a.chen@intel.com>
and fixed before the first mailing list submission.

Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Arnd Bergmann 2021-08-11 08:30:23 +01:00 committed by Russell King (Oracle)
parent 249dbe74d3
commit bdec014528
3 changed files with 99 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
arch/arm/kernel/sys_oabi-compat.c
View File

@ -80,6 +80,7 @@
#include <linux/socket.h>
#include <linux/net.h>
#include <linux/ipc.h>
#include <linux/ipc_namespace.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
@ -302,46 +303,52 @@ struct oabi_sembuf {
unsigned short __pad;
};
#define sc_semopm sem_ctls[2]
#ifdef CONFIG_SYSVIPC
asmlinkage long sys_oabi_semtimedop(int semid,
struct oabi_sembuf __user *tsops,
unsigned nsops,
const struct old_timespec32 __user *timeout)
{
struct ipc_namespace *ns;
struct sembuf *sops;
struct old_timespec32 local_timeout;
long err;
int i;
ns = current->nsproxy->ipc_ns;
if (nsops > ns->sc_semopm)
return -E2BIG;
if (nsops < 1 || nsops > SEMOPM)
return -EINVAL;
if (!access_ok(tsops, sizeof(*tsops) * nsops))
return -EFAULT;
sops = kmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
if (!sops)
return -ENOMEM;
err = 0;
for (i = 0; i < nsops; i++) {
struct oabi_sembuf osb;
err |= __copy_from_user(&osb, tsops, sizeof(osb));
err |= copy_from_user(&osb, tsops, sizeof(osb));
sops[i].sem_num = osb.sem_num;
sops[i].sem_op = osb.sem_op;
sops[i].sem_flg = osb.sem_flg;
tsops++;
}
if (timeout) {
/* copy this as well before changing domain protection */
err |= copy_from_user(&local_timeout, timeout, sizeof(*timeout));
timeout = &local_timeout;
}
if (err) {
err = -EFAULT;
} else {
mm_segment_t fs = get_fs();
set_fs(KERNEL_DS);
err = sys_semtimedop_time32(semid, sops, nsops, timeout);
set_fs(fs);
goto out;
}
kfree(sops);
if (timeout) {
struct timespec64 ts;
err = get_old_timespec32(&ts, timeout);
if (err)
goto out;
err = __do_semtimedop(semid, sops, nsops, &ts, ns);
goto out;
}
err = __do_semtimedop(semid, sops, nsops, NULL, ns);
out:
kvfree(sops);
return err;
}
@ -368,6 +375,27 @@ asmlinkage int sys_oabi_ipc(uint call, int first, int second, int third,
return sys_ipc(call, first, second, third, ptr, fifth);
}
}
#else
asmlinkage long sys_oabi_semtimedop(int semid,
struct oabi_sembuf __user *tsops,
unsigned nsops,
const struct old_timespec32 __user *timeout)
{
return -ENOSYS;
}
asmlinkage long sys_oabi_semop(int semid, struct oabi_sembuf __user *tsops,
unsigned nsops)
{
return -ENOSYS;
}
asmlinkage int sys_oabi_ipc(uint call, int first, int second, int third,
void __user *ptr, long fifth)
{
return -ENOSYS;
}
#endif
asmlinkage long sys_oabi_bind(int fd, struct sockaddr __user *addr, int addrlen)
{

3
include/linux/syscalls.h
View File

@ -1373,6 +1373,9 @@ long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf);
long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
unsigned int nsops,
const struct old_timespec32 __user *timeout);
long __do_semtimedop(int semid, struct sembuf *tsems, unsigned int nsops,
const struct timespec64 *timeout,
struct ipc_namespace *ns);
int __sys_getsockopt(int fd, int level, int optname, char __user *optval,
int __user *optlen);

84
ipc/sem.c
View File

@ -1984,46 +1984,34 @@ out:
return un;
}
static long do_semtimedop(int semid, struct sembuf __user *tsops,
unsigned nsops, const struct timespec64 *timeout)
long __do_semtimedop(int semid, struct sembuf *sops,
unsigned nsops, const struct timespec64 *timeout,
struct ipc_namespace *ns)
{
int error = -EINVAL;
struct sem_array *sma;
struct sembuf fast_sops[SEMOPM_FAST];
struct sembuf *sops = fast_sops, *sop;
struct sembuf *sop;
struct sem_undo *un;
int max, locknum;
bool undos = false, alter = false, dupsop = false;
struct sem_queue queue;
unsigned long dup = 0, jiffies_left = 0;
struct ipc_namespace *ns;
ns = current->nsproxy->ipc_ns;
if (nsops < 1 || semid < 0)
return -EINVAL;
if (nsops > ns->sc_semopm)
return -E2BIG;
if (nsops > SEMOPM_FAST) {
sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
if (sops == NULL)
return -ENOMEM;
}
if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) {
error = -EFAULT;
goto out_free;
}
if (timeout) {
if (timeout->tv_sec < 0 || timeout->tv_nsec < 0 ||
timeout->tv_nsec >= 1000000000L) {
error = -EINVAL;
goto out_free;
goto out;
}
jiffies_left = timespec64_to_jiffies(timeout);
}
max = 0;
for (sop = sops; sop < sops + nsops; sop++) {
unsigned long mask = 1ULL << ((sop->sem_num) % BITS_PER_LONG);
@ -2052,7 +2040,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
un = find_alloc_undo(ns, semid);
if (IS_ERR(un)) {
error = PTR_ERR(un);
goto out_free;
goto out;
}
} else {
un = NULL;
@ -2063,25 +2051,25 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
if (IS_ERR(sma)) {
rcu_read_unlock();
error = PTR_ERR(sma);
goto out_free;
goto out;
}
error = -EFBIG;
if (max >= sma->sem_nsems) {
rcu_read_unlock();
goto out_free;
goto out;
}
error = -EACCES;
if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
rcu_read_unlock();
goto out_free;
goto out;
}
error = security_sem_semop(&sma->sem_perm, sops, nsops, alter);
if (error) {
rcu_read_unlock();
goto out_free;
goto out;
}
error = -EIDRM;
@ -2095,7 +2083,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
* entangled here and why it's RMID race safe on comments at sem_lock()
*/
if (!ipc_valid_object(&sma->sem_perm))
goto out_unlock_free;
goto out_unlock;
/*
* semid identifiers are not unique - find_alloc_undo may have
* allocated an undo structure, it was invalidated by an RMID
@ -2104,7 +2092,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
* "un" itself is guaranteed by rcu.
*/
if (un && un->semid == -1)
goto out_unlock_free;
goto out_unlock;
queue.sops = sops;
queue.nsops = nsops;
@ -2130,10 +2118,10 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
rcu_read_unlock();
wake_up_q(&wake_q);
goto out_free;
goto out;
}
if (error < 0) /* non-blocking error path */
goto out_unlock_free;
goto out_unlock;
/*
* We need to sleep on this operation, so we put the current
@ -2198,14 +2186,14 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
if (error != -EINTR) {
/* see SEM_BARRIER_2 for purpose/pairing */
smp_acquire__after_ctrl_dep();
goto out_free;
goto out;
}
rcu_read_lock();
locknum = sem_lock(sma, sops, nsops);
if (!ipc_valid_object(&sma->sem_perm))
goto out_unlock_free;
goto out_unlock;
/*
* No necessity for any barrier: We are protect by sem_lock()
@ -2217,7 +2205,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
* Leave without unlink_queue(), but with sem_unlock().
*/
if (error != -EINTR)
goto out_unlock_free;
goto out_unlock;
/*
* If an interrupt occurred we have to clean up the queue.
@ -2228,13 +2216,45 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
unlink_queue(sma, &queue);
out_unlock_free:
out_unlock:
sem_unlock(sma, locknum);
rcu_read_unlock();
out:
return error;
}
static long do_semtimedop(int semid, struct sembuf __user *tsops,
unsigned nsops, const struct timespec64 *timeout)
{
struct sembuf fast_sops[SEMOPM_FAST];
struct sembuf *sops = fast_sops;
struct ipc_namespace *ns;
int ret;
ns = current->nsproxy->ipc_ns;
if (nsops > ns->sc_semopm)
return -E2BIG;
if (nsops < 1)
return -EINVAL;
if (nsops > SEMOPM_FAST) {
sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
if (sops == NULL)
return -ENOMEM;
}
if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) {
ret = -EFAULT;
goto out_free;
}
ret = __do_semtimedop(semid, sops, nsops, timeout, ns);
out_free:
if (sops != fast_sops)
kvfree(sops);
return error;
return ret;
}
long ksys_semtimedop(int semid, struct sembuf __user *tsops,